sparc64: Make special trap return path for TRAP_NMI().

We don't want the rtrap path to try and run softirqs or
anything like that when returning from a PIL==15 NMI.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 1 deletions

diff --git a/arch/sparc64/kernel/rtrap.S b/arch/sparc64/kernel/rtrap.S
index 6892cf556f45..fd3cee4d117c 100644
--- a/arch/sparc64/kernel/rtrap.S
+++ b/arch/sparc64/kernel/rtrap.S
@@ -132,6 +132,18 @@ __handle_signal:
                 ba,pt                   %xcc, __handle_signal_continue
                  andn                   %l1, %l4, %l1
 
+                /* When returning from a NMI (%pil==15) interrupt we want to
+                 * avoid running softirqs, doing IRQ tracing, preempting, etc.
+                 */
+                .globl                  rtrap_nmi
+rtrap_nmi:      ldx                     [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
+                sethi                   %hi(0xf << 20), %l4
+                and                     %l1, %l4, %l4
+                andn                    %l1, %l4, %l1
+                srl                     %l4, 20, %l4
+                ba,pt                   %xcc, rtrap_no_irq_enable
+                 wrpr                   %l4, %pil
+
                 .align                  64
                 .globl                  rtrap_irq, rtrap, irqsz_patchme, rtrap_xcall
 rtrap_irq:
@@ -161,8 +173,8 @@ rtrap_xcall:
                 call                    trace_hardirqs_on
                  nop
                 wrpr                    %l4, %pil
-rtrap_no_irq_enable:
 #endif
+rtrap_no_irq_enable:
                 andcc                   %l1, TSTATE_PRIV, %l3
                 bne,pn                  %icc, to_kernel
                  nop